Monitoring clutch fan

[theholycow]

The full grille block test (well, radiator block) on my truck did not cause the temperature to budge, not even slightly. It's got a clutch fan instead of an electric fan. Is there a way I can monitor the fan to know when it's running?

[suspendedhatch]

Mechanical fan? Not likely... unless you want to mount a hall effect sensor to it.

Don't trust OEM coolant temp gauges. By the time they tell you that you're overheating, you're already doing critical engine damage. For instance on my VX, the needle is in exactly the same position from 176 to 230 degrees! Yet above the temp when the rad fan comes on approx 205 F, the engine is suffering from accelerated wear. Heat kills engines.

[R.I.D.E.]

I didn't see problems with OEM temp guages, in 30 years of working on cars. Confirmed with touching the top hose with my hand and using a digital thermometer. Maybe your problems were with only Hondas, Hatch, or your individual vehicle.

I also demonstrated bad fan clutches by taking a shop rag and stopping the fan from the rear and spinning it backwards while the engione was running (no its not a misprint and it was a very effective demonstration, to confirm a bad clutch when the engine started overheating at idle).

Mercedes stated very clearly that their engines could operate without damage up to 256 degrees F, as long as the anitifreeze ratio was correct.

When a clutch fan "hooks up" you can easily tell the difference in the fan noise. If your grille block is to effective you could be loosing power driving the fan at greater speeds which will eat up some HP.

Probably better to switch to an electric fan.

regards
gary

[dkjones96]

Mechanical fans and grille blocks aren't the best combo in my experience. The block makes the fan itself run a little hotter and starts trying to move more air regardless of whether it can or not.

When I did my block it only lasted a day because I'd take off from a light and could hear the fan pulling hard and feel the car gain power as the fan let go once I was moving again.

Now, a FLEX fan is a different story.

[theholycow]

Maybe your problems were with only Hondas, Hatch, or your individual vehicle.

That's my guess as to the reason behind the common complaint of OEM gauges being inaccurate. I haven't compiled the statistics, but I wouldn't be surprised if all the bad gauges were Honda and/or Toyota.

My truck's gauge is definitely accurate and fast-responding. I admit I haven't taken measurements, but after nearly 180,000 miles I'm very familiar with it. The only way to make it rise from its normal spot is dragging a 6000 pound camper straight up a mountain, such that I can't actually maintain the speed I want, when the temperature outside is 85 degrees or higher. Doing so makes it rise rather quickly, and letting the engine rest makes it fall just as fast.

My tachometer, a gauge also often suggested as being inaccurate, now that's something that I have confirmed with measurements. Tachometers on my GM vehicles and my VW are definitely accurate and real-time.

When a clutch fan "hooks up" you can easily tell the difference in the fan noise. If your grille block is to effective you could be loosing power driving the fan at greater speeds which will eat up some HP.

This is exactly my fear. The setup I did today is just for testing to make sure it won't overheat, and when I do the actual grille block it's going to be more open. Today's work is between the transmission cooler and the A/C radiator, while the plan for the permanent grille block is in front of the grille (for aerodynamic effect as well as heat retention); it will have a decent sized hole for the tranny cooler, which will also let air in to cool the engine radiator.

Probably better to switch to an electric fan.

This can be done pretty inexpensively using fans from a junkyard. Unfortunately, "pretty inexpensive" is far beyond my available budget. I'm stuck with the clutch fan for the forseeable future.

[R.I.D.E.]

I have seen people drive fan clutch cars with the drive belt broken and they did not overheat as long as they were moving at over 25 MPH. The airlfow made the fan spin and the water pump kept turning with no belt.

regards
gary

[theholycow]

I was thinking about this more. How exactly is the clutch triggered? It must be thermostatically controlled, I'd guess with a bi-metal coil. Could I put a thermometer probe near wherever that is and watch temperature in that spot? Then I would know when the conditions should cause the fan to engage.

[R.I.D.E.]

Wire wound bimetallic spring on the front of the clutch opens and closes a bypass valve depending on temp of air flowing over the spring.

Believe me you can hear the difference in the fan noise when the clutch is engaged.

Many people think the clutch fans are not as efficient as an electric one. That may or may not be true, because when the airflow is sufficient the air flow will acutally spin the fan itself and relieve the necessity for the engine to do the same.

They are generally limited to a max speed of about 2500 RPM.

Of course blocking the grille could remove the air flow volume and cause the clutch to engage the fan to a much greater extent and sap engine power.

Your best bet may be to not block the portion directly in front of the radiator.

When you first start the engine the fan will wind up and you can hear it. When the clutch disengages (cold engine) the noise will become much lower in a few seconds. If the clutch siezes the fan noise will be much greater due to the fan being directly driven by the engine at much higher than its normal speed.

Be very careful of a weak clutch (old and worn out). It will not engage enough to properly cool the engine. The normal symptoms of this are overheating when sitting still.

regards
gary

[theholycow]

Believe me you can hear the difference in the fan noise when the clutch is engaged.

Alas, that's only true when the windows are open, the vehicle isn't moving, and accessories are off. Closing the windows and driving is enough to cover the sound. The OEM soundproofing is quite good.

Your best bet may be to not block the portion directly in front of the radiator.


There is no other portion. I guess I'll just experiment with it and see if it helps -- if I get an improvement in FE, should I really care whether or not the fan is running?

[dkjones96]

I don't know about that one THC. In my cars you can can always tell when the fan is working hard while you are accelerating. They can get loud.

[jeep45238]

My 1/4 marker on my saturn reads out at about 130*F and 170*F. That's a big varience.

Over 3/4 and I get worried.

[suspendedhatch]

That's my guess as to the reason behind the common complaint of OEM gauges being inaccurate. I haven't compiled the statistics, but I wouldn't be surprised if all the bad gauges were Honda and/or Toyota.

They're not bad. They're made that way intentionally. And it's not just confined to Honda/Toyota. Besides every other Japanese manufacturer, I have read documentation on Ford and GM vehicles that say the same thing. Although I've noticed most of their cars are made to run pretty damn cold.

If you ever install an aftermarket coolant temp gauge, you'll notice that it fluctuates all the time. Every time you come to a stop, the gauge rises rapidly. It's quite scary if you're not prepared for it. It would drive the average consumer absolutely insane. OEM's like their gauges to hang steadily in the middle. They only go into the red to warn you of a catastrophic failure so they can blame you for it later. It all has to do with the warranty and to the public's perception.

If you build the entire engine from iron you can run much hotter temps. Hondas are made from aluminum. The head AND the block. There are many advantages to aluminum as well as disadvantages. I know one thing is that I had a 4 cyl Toyota engine (aluminum head, iron block) that was substantially HEAVIER than a 6 cyl all aluminum engine. I've pulled Honda engines with just a floor jack. I've pulled Honda trannies with my bare hands (and the help of a friend).

Oh well, go ahead and criticize Honda all you want. We all know that when it comes down to hp/liter, fuel economy, reliability, number of recalls, ease of repair, low cost of repairs, Honda simply dominates the so-called domestics (assembled in Mexico from Taiwanese parts), and even the German built cars (which are well built but difficult and costly to maintain).

[2000mc]

after you know when and how much the fan slip speed is, what are you trying to do with that information?

[theholycow]

Seems I've touched a tender spot here...

They only go into the red to warn you of a catastrophic failure

My experience has shown otherwise. My GMC's gauge has never reached the red, but it has fluctuated around, matching my guess as to where it would go. I admit it doesn't fluctuate very far on a constant basis, though.

Oh well, go ahead and criticize Honda all you want.

You read the criticism, I merely ventured a guess about a technical issue.

Ok, I'll address your individual points:
hp/liter
Doesn't matter to me. If I'm looking for power, I prefer more displacement...I like torque, and I hate 7000 (or even 5000) rpm.

fuel economy

Honda's pretty much got a monopoly on that. GM and Ford do pretty well, though -- take a look at the Hypermile Sleepers thread. If Honda made something as large as a Grand Marquis, you can bet it would never hit 30mpg (http://www.gassavers.org/showpost.php?p=120027&postcount=42). Apparently the Pontiac G6 makes pretty respectable numbers (http://www.gassavers.org/showpost.php?p=122148&postcount=127), too...and fuel economy is quite opposite to Pontiac's modus operandi.

reliability, number of recalls, ease of repair, low cost of repairs

I see you're still living in 1992. Whose reliability statistics do you want to use? We'll start with JD Power's (http://www.jdpower.com/autos/ratings/dependability-ratings-by-brand/sortcolumn-1/ascending/page-#page-anchor) top 10:
Lexus, Mercury, Cadillac, Toyota, Acura, Buick, BMW, Lincoln, Honda, Jaguar

Honda's Acura luxury brand was beaten by Ford's Mercury brand and GM's Cadillac. Cadillac, really? My 1987 Cadillac's aluminum HT4100 engine was known for being crappy. Oh, wait, it's not 1987 anymore...

My mom's Acura had gremlins that they never managed to fix when she sold it at 50,000 miles. My dad's Toyota (or are you only a Honda defender, not a Japanese name defender?) has had far more and worse problems than my GMC.

Wouldn't you expect Honda and Acura to be right next to eachother? How about Buick and Chevrolet? Here's why they're not: Customer demographics have at least as much effect on reliability as manufacturing. Who buys Toyota? People who don't care if the car is exciting, they just want a car that will last forever. What do those people do with the car? They drive smooth and easy, and they maintain the car well. Who buys Honda? Well, the reliability buyers are diluted by the riceboys who think the "Fast & Furious" movies are a model for their way of life.

Honda simply dominates the so-called domestics (assembled in Mexico from Taiwanese parts)

I call them "domestic names", since globalization has broken all the old labels. You've provided one example. Another: 77% of all Hondas and Acuras are built in the US and Mexico, according to Honda.com (http://corporate.honda.com/press/article.aspx?id=200704023919).

and even the German built cars (which are well built but difficult and costly to maintain).

It was my impression that German cars are engineered well but built badly.

As for difficult and costly to maintain, the maintenance schedule for my VW (http://www.vw.com/dealer/MaintenanceSchedulesQuery.do?year=2007&engineCode=2.5L&carModel=RABBIT&TEMPLATENAME=maintenanceComplete&output=print) is quite friendly. I paid for the first oil change at 5,000 miles, did it myself at 10,000 miles with a minor learning curve (it turns out that the filter cartridge needs to be pushed into the filter housing with a strong shove), and the next scheduled service is at 20,000 (and every 10,000 after that). At 40,000 it's due for spark plugs (why didn't they use 100,000 mile plugs?) and an air filter. The synthetic oil is expensive, and it's hard to find a good selection of oils that meet VW's approval, but at every 10,000 miles it's not bad.

Anyway, I don't disagree that, on the whole, a Honda is the most logical choice if you're going to choose a car you've never seen or driven. However, for me, how the numbers add up on paper is only part of the decision. If I have a car in which I'm uncomfortable, or which I don't like for some other reason, it doesn't matter how well it adds up on paper, I will be miserable and unable to drive efficiently. It can even make me unhappy when I'm not driving, and my back or elbows hurt. Therefore, the first and most important quality of a vehicle is that I'm comfortable in it, like it, and want to drive it. For some people, a Honda fits those specifications. For me, it's a rare vehicle that fits and I accept it regardless of brand.

There's also the sheep factor -- I'm usually not about appearances, and I don't care to look cool, but I do rather dislike running with the herd* and only do it if there's some really compelling reason. That's the only abstract/conceptual problem I have with Honda, and the only reason I'd say anything about Honda that I expect to elicit that sort of reaction.

*: Sheep are usually described as running in flocks, but since I'm theholycow, I figured herd is more appropriate for me. :D

[theholycow]

after you know when and how much the fan slip speed is, what are you trying to do with that information?

I don't even know what "fan slip speed" means. I want the information so that I can optimize my modifications to avoid wasting power running the fan unnecessarily.

[Jay2TheRescue]

I think the only way to accurately monitor and/or control it is to rip out the belt driven fan and replace it with an electric.

-Jay

[2000mc]

drive at highway speed long enough for temps to stabilize, put the windows down, stop and take off again, taking note of the sound. then remove the grill block and repeat. if it sounds the same i wouldnt worry about it

[R.I.D.E.]

HC, if I understand correctly the fan slip speeds were what the thermal element controlled by restricting a bypass circuit. Maximum speed was about 2500 RPM regardless of engine speed. Minumum speeds considerably lower. I an not sure now but the 90-96 Nissan 300s used them. No reason to not go to electric if there was a real advantage.


I know this, the resistance bimetallic drive guages in the old Nissans I used to work on were the same as those in the early F15s. That is from the Colonel who headed the maintenance portion of the First Fighter squadron at Langley AFB. He was a good friend of mine. Same type guages in my 37 Ford as in a 1975 era F15 fighter seems to be a fairly sound testament to their effectiveness and reliability as well as accuracy. The design itself serves to dampen the readings somewhat, but not any serious inaccuracy or you can bet the USAF would not use them.

I have no doubt that faster acting guages would give you more erratic readings, especially if you drive aggressively and then stop and idle the engine. Heat transfer is always delayed somewhat, but it would be more pronounced in aluminum engines where the heat transfer rate is about 4 times higher than cast iron.

60,000 hours working on cars for a living should add up to some base of knowledge, combined with NEVER being summoned to court to defend my actions, a combination that equals treating people to a very high standard of conduct.

The Nissan aluminum block V6 engines would rival any manufactured on the planet. Even the old 3 liter cast iron blocks of the 84 300ZX were chosen by Dick Rutan for his Pond Racer at 1000 HP each, and they were 2 valve engines. Go back even further with Paul Neuman and the inline 6 engines made by Nissan at 600 HP with 24 hour race endurance. Their limitation was shearing off flywheel bolts at 9000 RPM, way beyond their design limits.

My first Honda was a totalled 77 Accord, purchased in 1978. I bought a CRX new in 1984, serial number 1018 produced in 7-83, one of the first off the assembly line.

First full time job working on cars was April 1969, probably before many here were born.

Personally when the old man died Honda lost some of its way as far as his guidance.

regards
gary

[theholycow]

Sorry about going off on that rant. I was tired and bored and I hate the pointless neverending brand-fan wars.

Anyway, the temperature gauge in my VW performed well this morning while comparing it to OBD data. When cold and warming up, it moved very slightly ahead of the OBD numbers. When at operating temperature, it seemed to track well with OBD; it stays around the 190 mark, but when I saw the OBD change I could look immediately and see the needle move just a tiny amount (or was it my imagination?).

Either way, the VW stayed near 190 according to OBD. I did my normal commute, but tried to raise the temperature. I did another 3rd gear redline run, then the normal 3000rpm highway cruising for a mile, then EOC for at least 45 seconds (followed by a short pulse and another, longer EOC, ad nauseum). It varied from 187 to 198 most of the time, rarely hitting 200, and once got up to 205 (a few minutes after the stress test I describe above).

That behavior is quite acceptable. I don't beat on it as hard during normal driving, and the permanent grille block will not be anywhere near as effective as the test I'm doing now.

[dkjones96]

190? What thermostat does that thing have?

When comparing my OBD to gauge numbers the temp needle doesn't really move at all when engine temps while operating range from normal cruising at a steady 200-201 degrees and a rock solid 208 degrees at idle.(In normal driving the engine VERY rarely gets below 200 degrees)

Now, I stress tested my car a few weeks ago on an incline at 90mph. I ran 5800 rpm wide open for about 9 minutes. Temps varied from 190-185. We're starting to get cold here though so that same situation would probably bring it below 160 now because as the revs climb the thermostat gets sucked open on this car and radiator output to the engine is almost always within 5 degrees of ambient. If it's less than 30 degrees outside and I floor the car from a stop up to highway speed(topping out second gear) it will bury the temp gauge in the cold from full operating temp.